However the WA Government has already said it would not conduct trials until it received the results of testing in New South Wales, due to start mid-next year.

Advice sought about product for trials, Hames says

WA Health Minister Kim Hames said he had recently sought advice about sourcing a product that could be used in trials at Princess Margaret Hospital.

"I'm investigating opportunities for WA to link in to the national trials, and issues around access to the clinical product," he said.

"Clinical trials could be legally conducted in WA under the right conditions, but they need to be run safely and ethically under medical supervision, and with an ultimate goal that sees national regulation so we don't have a piecemeal solution."

Dr Hames said therapeutic approval was needed to ensure pharmaceutical versions of cannabis extracts available overseas complied with Australian standards.

"Any decision on medicinal cannabis, the conditions to be treated, and safe methods of administration, must be made on the basis of robust scientific evidence," he said.

A spokesman for Dr Hames later issued a statement saying parents should not be using cannabis they had sourced themselves.

"The Minister deplores that practice because of the risk to the children," the spokesman said.

"For example, the parents would not be aware of the concentration they are administering. That is why the Minister supports proper trials in controlled settings."

Parents are not criminals: Epilepsy Action Australia

Epilepsy Action Australia chief executive Carol Ireland said parents who were treating their children with medicinal cannabis were not criminals.

She said one boy who had been suffering 500 seizures a day had suffered three seizures in 100 days after starting medicinal cannabis.

They are not criminals, they are looking after their kids and they are prepared to do whatever they can.

Carol Ireland, Epilepsy Action Australia

"It's a really difficult topic because you don't want to say to people 'go out and break the law', but very clearly there are some good results that are occurring," Ms Ireland said.

"[But there are] a couple of real concerns though. While some people are accessing a supply that seems to be pure and with the right ingredients in it, you don't know whether you are getting something that has contaminants in it.

"And because it's illegal at the moment, parents have got no way of going and actually having it tested if it is from a third party."

Ms Ireland said while clinical trials were needed, some families could not wait.

"If your child is having hundreds of seizures every single day, then their brains are already compromised and there is further long-term damage, and in some cases death," she said.

"So these parents are not prepared to sit back and see this happen. They are not criminals, they are looking after their kids and they are prepared to do whatever they can."

The New South Wales Government announced last month it had teamed up with a British pharmaceutical company for a world-first trial of a new form of medicinal cannabis, to be tested on children with severe drug-resistant epilepsy.